docs: def _parse_content_type(content_type: Optional[str]) -> Tuple[Optional[str], str]:
      """Tease out the content-type and character encoding.
  
      A default character encoding of UTF-8 is used, so the content-type
      must be used to determine if any decoding is necessary to begin
      with.
      """
      if not content_type:
          return None, "utf-8"
      else:
          type_, parameters = cgi.parse_header(content_type)
          encoding = parameters.get("charset", "utf-8")
          return type_, encoding